Focusing on passive intermodulation (PIM), a common instance of distortion in high-power multi-channel communication systems, the book introduces the concepts and technology of PIM. In the context of "space-ground-object" integrated communication and increasing spectrum resource constraints, the PIM problem is becoming increasingly prominent, while microwave components and system-level PIM are facing new challenges. Based on the experience and achievements in engineering practice of the China Academy of Space Technology in Xi’an, this title describes the basic theory, generation mechanism, analysis and evaluation methods, location detection and suppression techniques for microwave components of spacecraft PIM from a theoretical and engineering perspective. Furthermore, the latest achievements of microwave component PIM are outlined in depth, along with operational guidance and paths for further advancement. This book will be a useful reference for researchers, engineers and students interested in microwave technology, satellite technology and mobile communication technology. Wanzhao Cui is a professor at the National key Laboratory of Science and Technology on Space Microwave, at the China Academy of Space Technology, Xi’an, China. His current research interests include microwave technology and satellite communication. Jun Li is a professor at the National key Laboratory of Science and Technology on Space Microwave, at the China Academy of Space Technology, Xi’an, China. He is engaged in research on microwave technology and satellite communication. Huan Wei is a senior engineer at the National key Laboratory of Science and Technology on Space Microwave, at the China Academy of Space Technology, Xi’an, China. Her expertise is in the field of space microwave technology. Xiang Chen is a senior engineer at the National Key Laboratory of Science and Technology on Space Microwave, at the China Academy of Space Technology, Xi’an, China.